The instant invention relates to washing apparatus and in particular, to dispensers for dispensing a preselected quantity of detergent additives at a preselected time into washing liquid during a washing operation.
Conventional dishwashers effect cleaning by means of a preselected timed sequence of wash and rinse cycles in which different additives are introduced to the dishwashing chamber. Thus, detergent may be dispensed at different times during the wash cycle and rinse additives to provide improved rinsing of the washed dishes may be dispensed during the rinse cycle. Automatic dispensers which operate in preselected timed sequence have been provided in the past to effect the dispensing operation. However, because of the conditions under which such dispensers operate it is desirable to provide such dispensers with a minimal number of moving parts along with substantially clog-free construction. Likewise, for competitive reasons it is desirable to provide such dispensing structures which are extremely simple and economical in construction while still providing positive dispensing with minimum maintenance over long periods of use of the apparatus and elimination of any possibility of leakage.
Treating agent dispensers of the type used in automatic washing machines are typically located on the door of the machine. By opening the door access is provided to the dispenser container for filling the same. When the door is closed against the machine the dispenser container is generally vertical. The dispenser holds the treating agent in a storage position and, typically in response to a timer mechanism, moves the container to a dispensing position. All treating agent dispensers of this type purport to provide a sealed storage position to prevent washing liquid from entering the treating agent container. This is necessary since typically granular treating agents, such as detergents, will cake onto the treating agent container if they become moist or damp. It will be readily apparent that an imperfect seal between the container and its closure will act to retain a substantial portion of the treating agent in the container and may accordingly detract from the washing efficiency of the machine. Conversely, detergent dispensed before being required results in a premature release of chlorine (contained in most detergents) during the pre-wash or fill cycles. This also causes less effective washing.
When perfectly made or when made to rather small tolerances, the devices in the prior art function acceptably to seal the treating agent container in the storage position. It is inevitable in the mass production of automatic washing machines that the treating agent dispenser is subject to manufacturing tolerances of each component thereof as well as assembly tolerances. It will accordingly be apparent that in the mass production of automatic washing machines, manufacturing tolerances can cause inoperative or partially inoperative seals in a sizable percentage of dispensers. Previous devices have been shown such as commonly assigned U.S. Pat. No. 3,811,600 and 3,212,675 to overcome the above described disadvantages and problems, however, even these devices have remained relatively complicated. Another such device is shown in U.S. Pat. No. 3,565,291 which utilizes a solenoid mechanism integral with the dispenser housing for releasing the cover thereby exposing the detergent in response to a signal from the washer timer-programmer. Another solenoid actuated device is shown in U.S. Pat. No. 3,344,957. These devices also have many moving parts, are relatively expensive and require close manufacturing and assembly tolerances.